Hydrogen is utilized in a wide variety of industries ranging from aerospace to food production to oil and gas production and refining. Hydrogen is used in these industries as a propellant, an atmosphere, a carrier gas, a diluents gas, a fuel component for combustion reactions, a fuel for fuel cells, as well as a reducing agent in numerous chemical reactions and processes. In addition, hydrogen is being considered as an alternative fuel for power generation because it is renewable, abundant, efficient, and unlike other alternatives, produces zero emissions. While there is wide-spread consumption of hydrogen and great potential for even more, a disadvantage which inhibits further increases in hydrogen consumption is the absence of a hydrogen infrastructure to provide widespread generation, storage and distribution.
One way to overcome this difficulty is through the operation of hydrogen energy stations. At hydrogen energy stations, hydrogen generators. such as reformers or electrolyzers, are used to convert hydrocarbons or water to a hydrogen rich gas stream. The hydrogen rich gas stream can be purified to a high purity product. The gaseous hydrogen is then stored in stationary storage vessels at the hydrogen energy stations to provide inventory to fuel vehicles.
During vehicle fueling, the gaseous hydrogen is transferred from a stationary storage vessel to a vehicle's on-board storage tank. The current state of the art in hydrogen filling is to use cascade fill technology up to 350 Bar. This filling process causes an increase in pressure of the on-board storage tank of the vehicle and results in an increase in temperature due to the heat of compression of the hydrogen in the on-board storage tank. Temperatures in excess of 120° C. are possible. However, the on-board storage tanks that are used, such as Type III tanks with an aluminum liner and a composite cover, are limited to 85° C.
Current methods for controlling the fill process to prevent an over temperature of the on-board storage tank are to limit the fill rate or to monitor the temperature of the on-board storage tank and stop or reduce the flow if a high temperature is reached. First, limiting the fill rate results in long fill times. For example, the fill time can take up to twenty minutes. Second, monitoring the temperature of the on-board storage tank requires the connection of a temperature sensor in the on-board storage tank to the dispenser. For vehicles at a dispenser, calibration of the temperature sensor is critical to the safe filling of the vehicle during this “communications fill.” The on-board temperature sensor calibration is the responsibility of the vehicle owner rather than the dispenser and/or energy provider.
The present invention addresses the need to monitor the temperature of the on-board storage tank during vehicle filling by providing a method for calculating hydrogen temperature during vehicle fueling.